docs: add GitHub trending badge to README

Archon was #1 trending repo on GitHub. Add the Trendshift badge
between the tagline and the status badges.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: coleam00

README.md

@@ -8,6 +8,10 @@
   The first open-source harness builder for AI coding. Make AI coding deterministic and repeatable.
 </p>
 
+<p align="center">
+  <a href="https://trendshift.io/repositories/13964" target="_blank"><img src="https://trendshift.io/api/badge/repositories/13964" alt="coleam00%2FArchon | Trendshift" style="width: 250px; height: 55px;" width="250" height="55"/></a>
+</p>
+
 <p align="center">
   <a href="LICENSE"><img src="https://img.shields.io/badge/License-MIT-blue.svg" alt="License: MIT" /></a>
   <a href="https://github.com/coleam00/Archon/actions/workflows/test.yml"><img src="https://github.com/coleam00/Archon/actions/workflows/test.yml/badge.svg" alt="CI" /></a>